Process for the manufacture of acrylic acid copolymer and product

ABSTRACT

AN ACRYLIC ACID-OLEFIN COMPOUND HAVING A CHAIN STRUCURE IN WHICH THE UNITS OF ACRYLIC ACID-OLEFIN ALTERNATE AND A PROCESS FOR MANUFACTURING SAID COPOLYMER COMPRISING CONTACTING A MALEIC ANHYDRIDE-OLEFIN COPOLYMER WITH AN ALKALI METAL HYDROXIDE WHEREIN THE MOLE RATIO OF MALEIC ANHYDRIDE MOIETY IN THE COPOLYMER TO SAID HYDROXIDE IS ABOUT 1:1 IN THE PRESENCE OF WATER AND IN THE ABSENCE OF DECARBOXYLATION CATALYST AT A TEMPERATURE BETWEEN 120 AND 300*C. ACIDIFYING THE RESULTANT MIXTURE AND RECOVERING SAID COPOLYMER THEREFROM.

United States Patent Ofice Patented Aug. 8, 1972 ABSTRACT OF THE DISCLOSURE An acrylic acid-olefin copolymer having a chain strucure in which the units of acrylic acid-olefin alternate and a process for manufacturing said copolymer comprising contacting a maleic anhydride-olefin copolymer with an alkali metal hydroxide wherein the mole ratio of maleic anhydride moiety in the copolymer to said hydroxide is about 1:1 in the presence of water and in the absence of decarboxylation catalyst at a temperature between 120 and 300 C. acidifying the resultant mixture and recovering said copolymer therefrom.

BACKGROUND OF THE INVENTION This invention relates to acrylic acid-olefin copolymers in which the acrylic acid moiety and olefin moiety alternately form the copolymer chain and to the manufacture thereof. These copolymers are useful in the preparation of lacquer resins and water soluble stoving varnishes.

Copolymerization of acrylic acid or acrylic acid derivatives with equi-molar quantities of an olefinic monomer such as styrene leads to the formation of copolymers in which the acrylic acid or its derivatives are statistically distributed over the polymer chain. So far it has not been possible to synthesize a copolymer in which the acrylic acid and the copolymer alternatively form the chain. Catalytic decarboxylation processes taught in the art such as in German Pat. Nos. 445,565; 1,179,929 and 1,195,297 respectively decarboxylate by (l) utilizing steam plus sodium and calcuim carbonates or oxides on standard carriers and a temperature of 250-500 C., (2) utilizing a catalytic combination of trialkylphosphine plus arsenic or antimony trialkylarsine or stilbene coupled with a catalytic accelerator and a temperature of 60-260 C. and (3) utilizing a surface of metal of high conductivity such as copper in the presence of catalytic decarboxylating agents such as an oxide of copper, cadmium or silver at a temperature of 300-750 C. These prior processes which are directed towards decarboxylating maleic and/or fumaric acid and derivative monomers can either not be applied to the contemplated polymer reactants or will lead to incomplete conversions.

The desirability of being able to prepare an acrylic acidolefin copolymer wherein the chain structure alternately consists of the acrylic and olefin comonomers is the acrylic acid-olefin copolymer has a greater flexibility rendering it more crack resistant when functioning as a lacquer film.

SUMMARY OF THE INVENTION We have discovered a method of converting a maleic anhydride-olefin copolymer under non-catalytic conditions to an acrylic acid-olefin copolymer wherein the chain structure alternately consists of an acrylic acid moiety and olefin moiety. Further, we have discovered a method of controlled decarboxylation whereby the resultant copolymer has a chain structure of essentially alternating monomers, i.e., an olefin moiety on the one hand and an acrylic moiety on the other. Our invention further encompasses the novel resultant copolymer.

DETAILED DESCRIPTION OF THE INVENTION specifically the method of the invention comprises contactmg a maleic anhydride-olefin copolymer characterized by the formula:

atria where R R R R, R and R are hydrogen, alkyl or aryl of from 1 to 8 carbons and x is an integer of from 5 to 50 with an alkali metal hydroxide, e.g., NaOH, or KOH in the presence of water and in the absence of decarboxylation catalyst at a temperature between about and 300 C., preferably between ISO-200 C., utilizing a mole ratio of alkali metal hydroxide to maleic anhydride moiety of about 1:1, preferably 1:1. The water content normally constitutes between about 10 and 50 wt. percent of the reaction mixture and the reaction time is normally for a period of between 1 and 5 hours. The resultant reaction mixture is then acidified to precipitate the copolymer and the copolymer is normally separated from the reaction mixture by filtration and purified, if desired, advantageously by washing. Examples of acidification agents are dilute aqueous mineral acid, e.g., hydrochloric, sulfuric, phosphoric and nitric acids of between about 1 and 10 wt. percent concentration. A suitable material for washing the precipitated polymer is water.

The product copolymer can be characterized by the formula:

ghee R R R R R R and x are as heretofore de- In further explanation of the process, as heretofore stated, it provides a simple way of producing copolymers of alternating chain structure from acrylic acid or its derivatives in other monomers, e.g., alkenes and substituted alkenes. According to the invention, the maleic anhydride olefin copolymers produced by standard means from maleic anhydride and olefin monomers, e.g., alkenes and substituted alkenes of from 2 to 8 carbons such as styrene, indene, isobutylene, alpha-methylstyrene and diisobutylene.

The copolymers thus obtained which are known to have alternating chain structures are converted to a solution of the monoalkali salt by the contact of the alkali metal hydroxide so that one carboxyl group remains free for each anhydride group. This contact is normally conducted in an autoclave type of apparatus to separate out the free carboxyl group. There is obtained the alkali salt of the copolymer whose chain is alternately formed by the acrylic acid moiety and the olefin monomer. The degree of decarboxylation can be determined by measuring the acid number of the copolymer or the liberated carbon dioxide.

The carboxylic groups of the alternating chain structure copolymers obtained may be converted to esters, amides, etc. as desired. Moreover, the process permits the manufacture of copolymers whose chain structure alternatively consists of comonomers such as styrene on the one hand and of acrylic and maleic anhydride (the latter being present in any desired ratio) on the other merely stopping the decarboxylation when the desired acrylicmaleic acid ratio is reached.

The following chemical equations further illustrate the process of the invention utilizing styrene, maleic anhydride, sodium hydroxide and aqueous hydrochloric acid.

vby filtration,. washed with 5000 mls. of watergand drie'd.

having an acid number of 280 and a degree 'offd :amount of 69 parts by weight of pulverul entj moiety to the acrylic moiety. A

CH (B=O 4 It is particularly surprising in the processnofv the inven- 30 'tion that the decarboxylation of the copolymers isefr'e'cted at relatively low temperatures without catalyst,'at-100% conversion.

The product and by the following examples but are not to be construed as limitations thereof.

EXAMPLE I process of the inventionra're illustrated An amount of 301 parts by weight of maleic anhydridestyrene copolymer, having an acid number'of 496 (mg.

rKOH/ g. polymer and a K-value of 15), andq5 4 parts by lation to the acrylicacid-styrene copolymer;

EXAMPLE II Y;

An amount of 85 parts by weight of a inale isobutylene 'copolymer (acid number 630; and 19 parts by weight of sodium h-ydro' v in 2000 parts by'weight of waterQThis solutlor'r he ed in an autoclave to 160 C. during 5 hours taken after 4.5 hours showed 98.5% decarE the acrylic acid-isobutylene copolymer. U- o acidification of the solution with "300 ml. of hydrochloric acid the copolymer is 'precipat N with 2000 mls. of water; The purified precipi recovered corresponding to a 95% yieldoffaci'y aci styrene copolyme'r with an acid number of '0' spending" to IOO'percent' decai'boxylation of We claim: I 1. A process for the manufactureof copolymer whose ii chains alternately consistof an olefininoiety 5 an 75 I 5. A process inaaccordan'ce with claim 3 ac yl'ic acid moietycompris'ing contacting a:maleicwanhyfdr i'de olefin copolymer characterized b the formula:

. I .Rl

16 50- vvith an alkali metal hydroxide utilizing a mole "ratio of alkali metal hydroxide to -ma1eic acid moiety of about *1: 1 in fflie" presence of: between about 10-5 0: wt.

' percent Water based on the reaction mixture in the absence of: decarboxylatio'n I catalyst at a temperature t between about" 1'20r'jand 300-C. to form arr intermediate alkali metal copolymer" salt "and subsequently acidifying ..said "salt and recovering 'saidacrylic acid-olefin copolymer from acidified mixture char acterized by -the formula: qt

i R K /R 1 RF and x are a" heretofore 2. "A process in cordancewithclairn' 1- wherein said 3: Xpioc'ss 'iri'acco'rdance with claim "2 -wherein"said alkali rii't'alhydroxide is sodium hydroxide; and.v sa'id acidifying comprises contacting said intermediate copoly- "n'ii'alkali "metal salt with aqueous mineral acidtof-w between aboutl and w percent concentratiom 4.A'proces's in accordance with claim- 3 wherein said are hydrogen and R is phenyl.

- wherein isaid 'rfiineral acid is hydrochloric acid and said R R3, R and R? are hydrogen and'R "and R areimethyl.

" 65A co'poly'm'e'r' product whose chains alternately-consist ofair olefin rnoiety and arr'acrylic acid-moiety characterized by the formula:

product accordance with claim "6 1e Rsiafid sea -en e re 6 8. A product copolymer in accordance with claim 6 3,180,843 4/1965 Dickerson 26030.6 wherein R R R and R are hydrogen and R and R 3,557,070 1/1971 Anspon et a1. 260- 86.7

are methyl.

References Cited JOSEHH L. SCHOFER, Primary Exammer UNITED STATES PATENTS 5 J. KIGHT III, Asslstant Examiner 3,444,143 5/1969 Morris et a1 260-784 3,297,657 1/1967 Gray et a1. 26078.5 26080 P, M, 88.1 PC

m2? W AT PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,682,868 Datedug 19-7 Inventor) ,[QHANNE] WOLLNER, WOLFGANG TIET'Z, WILHELM NEIER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 lines 5-6, change "A. G. Rh einpreussen" to --De vut sch e Texaco Akt iengesellschaft-+.

Signed end jsealed this 26th dsy of November 1974.

(SEAL), Attest:

MCCOY M'. "mason J v C. MAR SHAI. .L DAYNIN v I Attesting Officer f r Commissioner ofv Patents 

